Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron

Abstract

The present study investigates the phenolic profile of exudates and extracts of the green algae Dunaliella tertiolecta, harvested in natural seawater in the absence (control) and in the presence of Cu(II) (315 and 790 nmol L(-1)) and Fe(III) (900 nmol L(-1)) in order to identify and quantify the phenolic compounds produced under metallic stress conditions. The presence of metal ions modifies the growth of cells and changes cell metabolism by producing phenolic compounds adapted to the solution. The use of reversed-phase high-performance liquid chromatography (RP-HPLC) permitted the identification of 14 phenolic constituents. The concentration and type of polyphenols detected in cell extracts and in solution are directly related with the metal and its concentration during growth cultures, achieving 1.4 times higher levels of polyphenols under 790 nmol Cu(II) L(-1) with respect to the control experiments. Microalga excretes polyphenols to be adapted to the environmental conditions. Gentisic acid, (+) catechin and (-) epicatechin, the most prominent phenolic compounds detected in the algae extracts, showed high antioxidant activity in inhibiting 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. This potent activity may be related to its presence in cells and exudates in high concentrations.

Phenolic Profile and Antioxidant Activity of Crude Extracts from Microalgae and Cyanobacteria Strains

“…Despite the reported antioxidant properties of the phenolic compounds and the potential of microalgae and cyanobacteria as sources of these compounds [17], few studies have focused on their identification and quantification in microalgae [18][19][20] and on the role played by phenolics in microalgae defense mechanisms against high ROS levels [21][22][23].…”

“…However, pioneer papers show that microalgae and cyanobacteria also contain phenolic and cinnamic acid derivatives at g levels on a dry weight basis [29,30] and evidences for microalgae polyphenols synthesis are clear [21][22][23]. Therefore, it is necessary to improve accurate methodologies to detect and quantify phenolics in microalgae and cyanobacteria, which help to explain the role played by these compounds [22,31].…”

Effect of Organic Fe-Ligands, Released by Emiliania huxleyi, on Fe(II) Oxidation Rate in Seawater Under Simulated Ocean Acidification Conditions: A Modeling Approach

“…The acidity constants (Equations 17,18) are in close alignment with those of -OH groups of phenolic compounds, (Herrero-Martínez et al, 2005) and -SH fractions of glutathionecontaining ligands (Poole, 2015). Significant amounts of low molecular weight organic material with thiolic and phenolic fractions are known to be generated in cultures of microalgae (Vasconcelos et al, 2002;Rico et al, 2013;López et al, 2015), including E. huxleyi (Dupont and Ahner, 2005;Strmečki et al, 2010;Jin et al, 2015), although these ligands can be also present in solution as monomers due to photochemical breakdown (Laglera and van den Berg, 2006;Li et al, 2015;Lu et al, 2016). Moreover, both thiol-and hydroxy-groups have been described as one of the most active groups binding divalent cationic metals in aqueous solution (Hider and Kong, 2011).…”

“…In this work, the presence of DUA E did not result in an increase of the oxidation rate, suggesting that E. huxleyi exudates include other types of organic ligands that are capable of binding Fe(II) and slowing the oxidation process. For example, phenolic compounds such as catechin and sinapic acid are part of the organic compounds exuded by eukaryote phytoplankton (Rico et al, 2013;López et al, 2015) that play an important role in the decrease of the Fe(II) oxidation rate .…”

Zinc toxicity stimulates microbial production of extracellular polymers in a copiotrophic acid soil

“…Exogenous organic substrate and heavy metal ion concentration are crucial factors influencing microbial EPS production and biofilm formation in these systems. For instance, silver ions and nanoparticles affect the composition of phototrophic biofilm in operated bioreactors (González et al., 2015), and copper and iron concentrations affect the profile of phenolic compounds exuded by marine microalgae (Rico et al., 2013, Lopez et al., 2015). …”